1. Field of the Invention
The present invention relates to a processing apparatus for removing an oxide film from a surface of an object to be processed and also relates to a processing method of removing the oxide film from the surface.
2. Description of the Related Art
Hitherto, as the method of removing native oxide films in fine holes formed in a wafer effectively, there is a surface treatment method as follows.
At first, by using of plasma technique, a mixture of N2 gas and H2 gas is activated to produce active gas species. Second, NF3 gas is added to the down flow of the active gas species in order to activate NF3 gas. Next, it is executed to allow the active gas species of NF3 gas to react with a native oxide film on the surface of the wafer thereby producing a product film. By heating the wafer to a designated temperature subsequently, the product film is sublimated for its removal.
As the apparatus used in such a method, there is known a processing apparatus which includes a processing container for accommodating a wafer therein, a NF3 active gas species generating unit for generating the active gas species of NF3 gas, heating means positioned outside the processing container in order to heat the wafer and a transparent window arranged between the heating means and the above object to allow heat energy from the heating means through. In this apparatus, it is executed to make the active gas species of NF3 gas to react with the native oxide film formed on the surface of the wafer, at a low temperature, thereby forming a product film. Next, by the heating means, the product film is heated to a predetermined temperature for its sublimation, removing the native oxide film.
In the above processing apparatus, however, if the heating process of the wafer has been completed and subsequently, a new wafer is loaded into the processing container for the low-temperature treatment, then the new wafer is undesirably heated due to heat radiated from the transparent window heated in the previous heating process. Therefore, it is necessary to wait for the transparent window to be cooled to a designated temperature, thereby causing the processing efficiency to be deteriorated remarkably.